5 things to know before the stock market opens Wednesday

Here are the most important news, trends and analysis that investors need to start their trading day:

• Wall Street to open flat, with earnings and Fed in focus
• Pfizer sells $7.8 billion in Covid shots in the Q2, raises 2021 guidance
• Biden considering Covid vaccine mandate for federal workers
• Big Tech reports blow out earnings, stocks mixed in premarket
• McDonald's earnings beat, driven by BTS promotion, new chicken sandwich

U.S. stock futures were flat Wednesday after Wall Street snapped its five-session winning streak and a run of record-high closes for the Dow Jones Industrial Average, S&P 500 and Nasdaq. The Federal Reserve ends its two-day July meeting Wednesday, with a policy statement at 2 p.m. ET and Fed Chairman Jerome Powell‘s news conference at 2:30 p.m. ET. Investors also get a flood of earnings to sift through, including Big Tech numbers from after the bell Tuesday. Facebook reports earnings after the bell Wednesday.

Pfizer is raising its 2021 sales forecast for its Covid vaccine by nearly 29% to $33.5 billion, as the delta variant spreads and scientists debate whether people need booster shots. In releasing better-than-expected quarterly earnings and revenue, Pfizer also said Wednesday it sold $7.8 billion in Covid shots in the second quarter. Pfizer fell roughly 1% in premarket trading. Earlier this month, Pfizer said it was seeing signs of waning immunity induced by its Covid vaccine with German drugmaker BioNTech, and planned to ask the FDA to authorize a booster dose.

The White House is strongly considering requiring federal employees to show proof of Covid vaccination or submit to regular testing and wear a mask. President Joe Biden suggested Tuesday that expanding that mandate to the entire federal workforce was “under consideration.” The Department of Veterans Affairs on Monday became the first federal agency to require vaccinations for its health workers.

Apple fell 1% in premarket trading after warning the negative impact of the global chip shortage would worsen this quarter. That caution came after Apple reported better-than-expected quarterly earnings of $1.30. Revenue surge past estimates as well, driven by a 50% pop in iPhone sales.

Microsoft beat estimates by 25 cents with quarterly earnings of $2.17 per share, while revenue beat estimates as well on continued strong growth in the company's cloud computing business. Microsoft continued to benefit from the pandemic shift to working and learning from home. Microsoft rose slightly in the premarket.

Alphabet earned $27.26 per share for its latest quarter, well above estimates. Revenue for the Google parent also trounced forecasts, benefiting from the ongoing surge in online ad spending. Alphabet jumped nearly 4% in Wednesday's premarket.

McDonald's on Wednesday reported double-digit U.S. same-store sales growth compared with pre-Covid 2019 levels in its latest quarter. Strong demand for its BTS meal promotion and new chicken sandwich boosted those numbers. Per-share earnings of $2.37 and revenue of $5.89 billion both exceeded expectations. McDonald's fell slightly in the premarket.

Boeing reported its first quarterly profit in almost two years Wednesday, boosted by a surge in deliveries of commercial jetliners as airlines began recovering from the pandemic. Earnings of 40 cents per share beat estimates for an 83 cent loss. Revenue of $17 billion also exceeded expectations. The stock jumped about 3.5% in the premarket.

— CNBC's Peter Schacknow and The Associated Press contributed to this report. Follow all the market action like a pro on CNBC Pro. Get the latest on the pandemic with CNBC's coronavirus coverage.